It is known that some peptide boronic acid compounds are proteasome inhibitors, and they represent an important strategy in cancer therapy. Besides the marketed drug VELCADE® (Bortezomib or chemical name as [(1R)-3-methyl-1-[[(2S)-1-oxo-3-phenyl-2[(pyrazinylcarbonyl) amino]propyl]amino]butyl] boronic acid) for the treatment of multiple myeloma, other types of cancers, and amyloidosis. There are a number of structurally different peptide boronic acids at various stages of clinical trials. One major issue of this group of boronic acids as (active pharmaceutical ingredient (API) is that they are not very stable at ambient conditions. The drug VELCADE®, for example, needs to be stored at below ambient temperature and kept away from light. Partially related to its instability, the drug VELCADE® is formulated as an injection mixture, and patients must go to doctors' offices or hospitals for drug administration. Boronic acids are known to form many boronic acid derivatives, such as boronates and boronate esters. Boronates and boronate esters are able to be converted back to boronic acid under certain conditions.
The present invention describes a group of boron-containing compounds, such as boronate, boronate esters, boranamines, boranediamines, boranamine thioesters, and boronic mono/di-thioesters, that are stable at ambient conditions. They can be formulated as both liquid and solid drugs. Therefore, the bioactive component of the drug can be circulated longer in the human body and reach more areas unavailable to the direct injection into blood vessels.